This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This protocol proposes to measure gene expression patterns in osteophytes to determine the genetic basis for osteophyte formation. Specifically, the investigators will measure RNA (microarray screening) in tissue collected from patients undergoing total knee replacements. Patterns of RNA expression will be compared between osteophytes, normal articular cartilage, and degenerative cartilage. Samples will be collected through the Tissue Donation Program.